Plus of course you can toggle though the Aspect Ratios available by pressing "a" on a keyboard, with the setting displayed at the bottom of the screen.
Or, your can access the On Screen Display using the up and down arrow keys on either the remote or a keyboard. The OSD menus allow you to change the Aspect Ratio and/or the Zoom of the image on screen.
Closed Captions (Teletext page 801) still isn't available in MC21.0.14. The information isn't even passed through to your TV by MC unfortunately, so you can't even turn it on in your TV settings when playing TV via MC. I just tested it on my Samsung smartTV, connected from my HTPC directly via HDMI. Teletext works if watching a TV channel directly on the TV, but via MC from the HTPC the TV just says that the service is not available.